ABSTRACTAn aneurysmal bone cyst (ABC) is a benign, locally proliferative vascular disorder of non-neoplastic osseous lesions in children and young adults. Seventy-five percent of ABCs occur before the age of 20 years. They comprise 1.4% of all primary bone tumors, and commonly occur in the long bones. Spinal ABCs are much rarer. We present to you one such rare case of ABC involving the lumbar spine which was successfully treated with surgery. The clinical pathological and radiological features are described. The treatment options available are discussed.

Mentions:
A 17-year-old girl presented with one week history of severe localized lower back pain at fourth lumbar vertebral level which increases on lying supine. On examination, she had left dorsiflexion and EHL weakness of grade 4/5 with sensory impairment in left L5 dermatome. Local tenderness on palpation was present. Her bladder and bowel habits were normal. There was no previous history of trauma. X-rays showed osteolytic lesion involving the L4 vertebral body with winking owl sign on AP views [Figure 1a]. Computed tomography (CT) scan of lumbar spine with reconstruction showed lytic expansile lesion involving the L4 vertebral body and left pedicle [Figure 1b–e]. Magnetic resonance imaging (MRI) showed characteristic findings of aneurysmal bone cyst with multiple fluid-fluid levels [Figure 2a–d]. There was extension of the lesion into the spinal canal and pressure on the left sided nerve roots. She underwent left transpedicular approach and complete excision of the lesion followed by pedicle screw fixation. The lesion had a dark red fleshy appearance with moderate vascularity. The lesion was encasing the nerve root on the left side, which was carefully dissected and excised. Multiple blood filled cysts involving the L4 vertebral body were encountered. The tumor was totally extradural and was completely excised. Histopathology of the lesion showed uniformly distributed osteoclast type giant cells having multiple nuclei [Figure 3]. There were few cysts containing hemorrhage and were lined by histiocytes and osteoclast giant cells. These features were suggestive of secondary aneurysmal bone cyst.

Mentions:
A 17-year-old girl presented with one week history of severe localized lower back pain at fourth lumbar vertebral level which increases on lying supine. On examination, she had left dorsiflexion and EHL weakness of grade 4/5 with sensory impairment in left L5 dermatome. Local tenderness on palpation was present. Her bladder and bowel habits were normal. There was no previous history of trauma. X-rays showed osteolytic lesion involving the L4 vertebral body with winking owl sign on AP views [Figure 1a]. Computed tomography (CT) scan of lumbar spine with reconstruction showed lytic expansile lesion involving the L4 vertebral body and left pedicle [Figure 1b–e]. Magnetic resonance imaging (MRI) showed characteristic findings of aneurysmal bone cyst with multiple fluid-fluid levels [Figure 2a–d]. There was extension of the lesion into the spinal canal and pressure on the left sided nerve roots. She underwent left transpedicular approach and complete excision of the lesion followed by pedicle screw fixation. The lesion had a dark red fleshy appearance with moderate vascularity. The lesion was encasing the nerve root on the left side, which was carefully dissected and excised. Multiple blood filled cysts involving the L4 vertebral body were encountered. The tumor was totally extradural and was completely excised. Histopathology of the lesion showed uniformly distributed osteoclast type giant cells having multiple nuclei [Figure 3]. There were few cysts containing hemorrhage and were lined by histiocytes and osteoclast giant cells. These features were suggestive of secondary aneurysmal bone cyst.

Bottom Line:
Spinal ABCs are much rarer.The clinical pathological and radiological features are described.The treatment options available are discussed.

ABSTRACTAn aneurysmal bone cyst (ABC) is a benign, locally proliferative vascular disorder of non-neoplastic osseous lesions in children and young adults. Seventy-five percent of ABCs occur before the age of 20 years. They comprise 1.4% of all primary bone tumors, and commonly occur in the long bones. Spinal ABCs are much rarer. We present to you one such rare case of ABC involving the lumbar spine which was successfully treated with surgery. The clinical pathological and radiological features are described. The treatment options available are discussed.